1-Hydroxy-1-(4-aminophenyl polymethine) naphthalan compounds and pressure-sensitive recording system therewith

ABSTRACT

Disclosed are normally substantially colorless chromogenic 1hydroxy-1-(4-aminophenyl polymethine) naphthalan color precursor compounds having the following structural formula:   WHEREIN EACH R represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms and wherein n is an integer from 1 to 3. These compounds are initially substantially colorless and are capable of becoming highly colored when brought into reactive contact with many conventional Lewis acid materials and the like. Accordingly these compounds are highly useful as a component of pressure-sensitive copying papers.

[ Dec. 23, 1975 1-HYDROXY-1-(4-AMINOPHENYL POLYMETHINE) NAPHTHALAN COMPOUNDS AND PRESSURE-SENSITIVE RECORDING SYSTEM THEREWITH [75] Inventor: Derek J. Alsop, North Tonawanda,

[73] Assignee: Moore Business Forms, Inc.,

Niagara Falls, NY.

22 Filed: Nov. 21, 1974 21 Appl. No.: 525,990

[52] [1.5. CI. 428/411; 260/240 D; 260/345.2; 427/151; 428/323 [51] Int. Cl. C071) 311/92; C08K 5/15 [58] Field of Search 260/240 D, 335, 345.2; 427/ 151 [56] References Cited UNITED STATES PATENTS 3,463,655 8/1969 Imamija et al. 428/411 3,492,295 l/l970 Sureau et al 260/345.2 X 3,641,011 2/1972 Lin ct a1. 260/240 G 3,832,212 8/1974 Jenkins et a]. 428/411 FOREIGN PATENTS OR APPLICATIONS 1,539,954 10/1968 France 260/240 D Primary Examiner-Allen B. Curtis [57] ABSTRACT Disclosed are normally substantially colorless chromogenic l-hydroxy-1-(4-aminophenyl polymethine) naphthalan color precursor compounds having the following structural formula:

OH R O cH=cH) wherein each R represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms and wherein n is an integer from 1 to 3. These compounds are initially substantially colorless and are capable of becoming highly colored when brought into reactive contact with many conventional Lewis acid materials and the like. Accordingly these compounds are highly useful as a component of pressure-sensitive copying papers.

10 Claims, N0 Drawings l-HYDROXY-1-(4-AMINOPHENYL POLYMETHINE) NAPHTHALAN COMPOUNDS AND PRESSURE-SENSITIVE RECORDING SYSTEM THEREWITH I BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to initially colorless chromogenic, color precursor compounds having particular utility in the field of carbonless copying. The compoundsof the present invention may be utilized, for example, in the production of self-marking impact papers of the transfer or manifolding type wherein a first marking ingredient is carried on one sheet of paper for reaction with a second marking ingredient normally carried on a mating sheet of paper. Specifically the invention relates to a family of chromogenic lhydroxy-l-(4-aminophenyl polymethine) naphthalan color precursor compounds having the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl group having from 1 to 5 carbon atoms and wherein n is an integer from 1 to 3.

2. Description of the Prior Art Impact or pressure sensitive carbonless transfer papers have recently come into wide usage in the United States and throughout the world. Ordinarily, such papers are printed and collated into manifolded sets capable of producing multiple copies. In this connection, pressure applied to the top sheet causes a corresponding mark on each of the other sheets of the manifolded set.

The top sheet of paper, upon which the impact or pressure is immediately applied, ordinarily has its back surface coated with microscopic capsules containing one of the reactive ingredients which produce a mark. A receiver sheet, placed in contact with such back face of the top sheet has its front surface coated with a material having a component reactive with the contents of the capsules so that when capsules are ruptured upon impact by stylus or machine key, the initially colorless or substantially colorless contents of the ruptured capsules react with a coreactant therefor on the receiver sheet and a mark forms on the receiver sheet corresponding to the mark impressed by the stylus or machine key.

In the art, impact transfer papers are designated by the terms CB, CFB and CF, which stand respectively for coated back", coated front and back and coated front. Thus, the CB sheet is usually the top sheet and the one on which the impact impression is directly made; the CFB sheets are the intermediate sheets, each of which have a mark formed on the front surface thereof and each of which also transmits the contents of ruptured capsules from its back surface to the front of the next succeeding sheet; and the CF sheet is the last sheet and is only coated on its front surface to have an image formed thereon. The CF sheet is not normally coated on its back surface as no further transfer is desired.

While it is customary to coat the capsules on the back surface and to coat the co-reactant for the capsules contents on the front surface of each sheet, this procedure could be reversed if desired. Further, with some systems, coatings need not be used at all and the coreactive ingredients may be carried in the sheets themselves, or one may be carried in one of the sheets and the other may be carried as a surface coating. Further, the reactants may both comprise microencapsulated liquids. Patents illustrative of many of the various kinds of systems which may incorporate such coreactive ingredients and which may be used in the production of manifolded transfer papers include, for example U.S. Pat. No. 2,299,694 to Green, U.S. Pat. No. 2,712,507 to Green, U.S. Pat. No. 3,016,308 to Macaulay, U.S. Pat. No. 3,429,827 to Ruus and U.S. Pat. No. 3,720,534 to Macaulay et al.

The most common variety of carbonless impact transfer paper, and the type with which the compounds of the present invention are preferably utilized, is the type illustrated, for example, in Green (507) and Macaulay (308) wherein microscopic capsules containing a liquid fill comprising a solution of an initially colorless chemically reactive color forming dye precursor arecoatedon the back surface of the sheet, and a dry coating of a co-reactant chemical for the dye precursor is coated on the front surface of a receiving sheet.

Many color precursors useful in connection with carbonless copying systems are known to those skilled in the art to which the present invention pertains. For example, specific reference is made to the color precursors mentioned in the patent to Phillips, Jr. et al, U.S. Pat. No. 3,455,721 and particularly to those listed in the paragraph bridging columns 5 and 6 thereof. Other color precursors are disclosed in U.S. Pat. No. 3,703,397 and U.S. Pat. No. 3,713,863 to Lin et al. These-color precursor materials are capable of reacting with a CF coating containing an acidic material such as the acid-leached bentonite-type clay disclosed in application Ser. No. 125,075 to Baxter filed Mar. 17, I971, the-entirety of which is hereby specifically incorporated by reference, or the acid-reactant organic polymeric. material disclosed in the Phillips, Jr. et al. 721 patent.

Many of the color precursors disclosed in the patents referred to above, are capable of undergoing an acidbase type reaction with an acidic material. Other previously known color precursors are the spiro-dipyran compounds disclosed in the patent to Harbort, U.S. Pat. No. 3,293,060 with specific reference being made to the disclosure of the 060 patent extending from column 11, line 32 through column 12, line 21. The color precursors disclosed in the patents listed above are initially generally colorless and capable of becoming highly colored when brought into contact with an acidic layer such as an acid-leached bentonite-type clay or an acid-reacting polymeric material, or the like.

Generally speaking, the color precursor materials disclosed above are dissolved in a solvent and the solube mentioned that the exact nature of the capsule itself is not critical as long as the same is capable of containing the color precursor and can be ruptured by the application of pressure in accordance with conventional carbonless copying procedures. Solvents known to be useful in connection with dissolving color precursors include chlorinated biphenyls, vegetable oils (castor oil, coconut oil, cotton seed oil, etc.) esters (dibutyl adipate, dibutyl phthalate, butyl benzyl adipatc, benzyl octyl adipate, tricresyl phosphate, trioctyl phosphate, etc.), petroleum derivatives (petroleum spirits, kerosene, mineral oils, etc.), aromatic solvents (benzene, toluene, etc.), silicone oils, or combinations of the foregoing. Particularly useful are the alkylatcd naphthalene solvents disclosed in US. Pat. No. 3,805,463 to Konishi et al.

For a disclosure of acidic coatings which are capable of convertng the color precursors into their highly colored form, reference is made to the disclosures of US. Pat. Nos. 3,622,364; 3,330,722; 3,389,007 and 3,293,060, as well as to the disclosure of Baxter application Ser. No. 125,075 referred to above.

In the color forming systems outlined above, as will be appreciated by those skilled in the art, the color precursors are conventionally contained in pressure rupturable microcapsules which are included in the back coatings of the sheets of carbonless copying manifolded sets. Further, it will be appreciated that the acidic coating are generally utilized as from coatings with the color precursor material in a solvent therefor being transferred from an adjacent back coating to the acidic layer front coating upon rupture of the capsules which contain the color precursor material.

SUMMARY OF THE INVENTION It is an object of this invention to provide new and improved compounds having chromogenic properties and which may be incorporated in a paper sheet or coated onto the surface thereof to provide a manifolding unit, and which are, moreover, useful in carrying out improved methods of marking involving reactive contact wth a color-activating material to yield vividly colored reaction products in areas where marking is desired.

It is another object of this invention to provide chromogenic compounds which are substantially colorless or only slightly colored offering a new and improved variety of chromogenic characteristics and yielding novel vividly colored substances upon contact with color-activating materials.

It is a further object of this invention to provide new and improved, normally substantially colorless, chro-- OH R mogenic substances yielding colored reaction products when in placed in reactive contact with Lewis acid materials. l

The foregoing objects are achieved by the provision of a family of substantially colorless chromogenic lhydroxy-I-(4-aminophenyl polymethine) naphthalan color precursor compounds having the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl group having from I to 5 carbon atoms and n is an interger from I to 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a family of normally substantially colorless chromogenic l-hydroxyl (4-aminophenyl polymethine) naphthalan color precursor compounds having the following structural formula:

CH 0 ,R

"s =TH I I \(u t I ON I wherein each R represents either a hydrogen atom or a lower alkyl group having from I to 5 carbon atoms and wherein n is an integer from 1 to 3. These compounds are initially substantially colorless; however, when brought into contact with a solid Lewis acid electron acceptor material such as the acid-leached bentonitetype clay disclosed in the application of Baxter, Ser. No. 125,075, they may be converted into a highly colored form. Various other solid acidic materials which are generally capable of converting these compounds into their highly colored form are disclosed in US. Pat.

Nos. 3,622,364; 3,330,722; 3,389,007 and 3,293,060

referred to above.

The naphthalan compounds of the present invention wherein n I may be prepared by reacting one mol of a p-amino benzaldehyde compound with a hydroxy naphthalan compound in the presence of HCl and thereafter neutralizing the reaction product with a base in accordance with the following formula:

The foregoing hydroxy naphthalan compound is prepared by treating 1,8-naphthalide with cH -Mgl'in accordance with the following formula:

0 +H,o CH3 M3 1 wherein n 2, a 3-(p-aminophenyl) propenal compound having the formula ,4 C .2 C R 0 may be used and for n 3, a S-(p-aminophenyl) pentadienal compound having the formula H H H H may be used in lieu of the p-aminobenzaldehyde.

EXAMPLE 1 100 gms of acenaphthenequinone were added to 500 ml of an aqueous solution containing 30 percent KOH by weight and the mixture was heated with constant stirring at 150C for about minutes. The reaction mixture was then diluted with distilled water and filtered and the filtrate was acidified with HCl. The white precipitate which formed was separated by filtration and was dissolved in an aqueous solution containing 10 percent Na CO by weight. This latter solution was treated with charcoal and the product was reprecipitated wich HCl. The reprecipitated solids were filtered and l 1 1 gms of 1,8-naphthaldehydic acid having a melting point of 165 to 170C were recovered.

EXAMPLE ll 1 11 grams of 1,8-naphthaldehydic acid produced in accordance with EXAMPLE I were dissolved in 3330 ml of 30% KOH solution and 1 10 ml of formalin were added to the solution. The reaction mixture was heated to about 60C and was stirred at the temperature for about 3 /2 hours. After the first hour of stirring, an additional 55 ml of formalin were added. The reaction mixture was filtered, cooled and acidified with concentrated HCl. The white precipitate which formed after acidification was collected on a filter and was washed first with 600 ml of a 5% NaHCO solution and then with distilled water. The yield was 57 grams. 52.4 gms of this product were recrystallized several times from high boiling Ligroin and the yield was 42.5 gms of recrystallized 1,8-naphthalide.

an, M I(oH) EXAMPLE III 9.2 grams (approximately 0.05 mole) of 1 ,8-naphthalide produced in accordance with EXAMPLE 11 were added to 700 ml of anhydrous ether in a 1000 ml 2 neck boiling flask fitted with a condensor and a drying tube. After the 1,8-naphthalide was completely dissolved in the either, 16.5 ml of a 3.18 molar aqueous solution of CH Mgl, were added dropwise while the solution was stirred. Immediately upon beginning the addition of the CH Mg1, a white precipitate appeared and the ether began to boil. The Cl-l Mgl was added at a rate to maintain a controlled boil in the flask. After all of the CH Mgl had been added, the reaction mixture was refluxed using a heating mantle for about 30 minutes and then ml of water were added dropwise at a controlled rate to maintain a slow boil in the flask. The reaction mixture was placed in a separatory funnel and the insoluble Mgl(Ol-l) was removed. The remaining ether layer was dried with Na SO and the ether was evaporated using a steam bath to leave about 9.0 gms of an almost colorless oily product which was a hydroxy naphthalan compound having the following structural formula:

0H an,

EXAMPLE IV 2.00 grams (approximately 0.01 mole) of the hydroxy naphthalan product produced in accordance with EXAMPLE Ill and 1.50 grams (approximately 0.01 mole) of p-dimethylaminobenzaldehyde were dissolved in 10 ml of glacial acetic acid and then HCl gas was bubbled through the resultant solution for about 10 minutes until the color of the solution had become intensely brown. This brown solution was poured into 300 ml of water to present an intensely blue solution of the dye. 3.2 grams of a 1-hydroxy-1-(4-dimethylaminophenyl polymethine) naphthalan color precursor were precipitated by neutralizing the blue solution with an aqueous 15% NH solution. The naphthalan precursor was dissolved in ethanol and was reprecipitated with water. After reprecipitation, filtration and drying, the yield was 1.0 grams of a pale yellow solid having the following structural formula:

0H 0 CH 7 EXAMPLE V 0.50 gm of the naphthalan product produced in accordance with EXAMPLE IV was admixed with 10.0 grams of R-300 solvent (a commercial product of Kureha Corporation of America which is a mixture of isomeric diisopropyl naphthalenes and is apparently generally disclosed in US. Pat. No. 3,806,463 to Konishi et al.) and this admixture was warmed slightly on a hot plate until a clear solution (solution A) was obtained. Thereafter solution A was allowed to cool to room temperature. (When a small quantity of solution A was applied to an acidic clay coating on a paper substrate, a violet color appeared.) Then, 1.63 gms of terephthaloyl chloride were added to 5.0 gms of R-300 solvent and this mixture was also warmed slightly on a hot plate until a clear solution (solution B) was obtained. Solution B was then allowed to cool to room temperature. After solutions A and B were prepared, 50 gms of an aqueous solution containing 2.0 weight percent Elvanol 50-42 (a commercial product of E. l. dePont de Nemours which is a polyvinyl alcohol with 87 to 89% hydrolysis and a viscosity of 35 to 45 cps in a 4% aqueous solution at 20C) were placed in a semimicro Waring blender and then solutions A and B were mixed together at room temperature and the resultant solution was added to the Elvanol solution in the blender. The blender was activated and high shear agitation was continued for about 2 minutes until an emulsion having a dispersed phase particle size of about 2 to microns was obtained. In this emulsion, the aqueous solution containing the Elvanol polyvinyl alcohol formed the continuous phase and the solution containing the R-300 solvent, the l-hydroxy-l-(4- dimethylaminophenyl polymethine) naphthalan and terephthaloyl chloride formed the dispersed phase. The emulsion was then transferred to a suitable container such as a beaker and was stirred with a variable speed mechanical stirrer at 300 to 500 rpm while an aqueous .solution containing 0.93 gms of diethylene triamine,

0.72 gms ofsodium carbonate and 10 ml of water was added. Stirring was continued at room temperature for about 24 hours until a stable pH of about 8.0 was ob served. At this time, the particles of dispersed phase had become individually encapsulated in a polyamide shell. The slurry containing the microcapsules and having the Elvanol polyvinyl alcohol binder in the continuous phase was then drawn down on a 13 pound neutral base continuous bond paper sheet at a coating weight of approximately 2.34 to 3.04 gms per square meter and the coated sheet was oven dried at a temperature of 1 10C for about 30 to 45 seconds. The dry coating on the paper sheet was white. The dry coating of microcapsules containing the l-hydroxy-l-(4-dimethylaminophenyl polymethine) naphthalan compound was then brought into contact with an acid-leached clay coating on the surface of another sheet of paper and when an impression was made on the reverse side of the sheet coated with microcapsules a corresponding light violet colored reproduction of such impression immediately appeared on the acid-leached clay coatmg.

While the foregoing Example specifically discloses the production and use of a l-hydroxy-l-(4-dimethylaminophenyl polymethine) naphthalan compound of the present invention wherein n 1, it is pointed out that the present invention also contemplates and specifically encompasses the similar production and use of 1-hydroxy-l-(4-aminophenyl polymethine) naphthalan compounds as disclosed above wherein the amino nitrogen atom carries either hydrogen atoms, methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups or any mixture of two of the foregoing and wherein n l, 2 or 3. Moreover, other solvents for color precursors are known to those skilled in the art to which this invention pertains and any solvent which does not substantially interfere with the formulation of color when the color precursor is contacted with a co-reactant may be utilized.

It is also to be noted that the compounds of the present invention are useful generally in the production and generation of colored marks and it is not critical to the present invention that the same be utilized in a copying system or in a microencapsulated form.

I claim:

1. A l-hydroxy-l-(4-aminophenyl polymethine) naphthalan compound having the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl group having from 1 to 5 carbon atoms and wherein n is an integer from 1 to 3.

2. A compound as set forth in claim 1 having the following structural formula:

cu=cun 3. A method for preparing a naphthalan compound as set forth in claim 1 comprising reacting one molar 5 equivalent of a p-aminobenzaldehyde compound with one molar equivalent of a hydroxy naphthalan compound having the following structural formula:

OH 0 CH 5. A method for preparing a naphthalan compound as set forth in claim 1 comprising reacting one molar equivalent of a S-(p-aminophenyl) pentadienal compound with one molar equivalent of a hydroxy naphthalan compound having the following structural formula:

p-dime- LII comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim 1.

8. In a pressure-sensitive recording system comprising a layer of microcapsules containing a substantially colorless color precursor compound and a layer of an electon-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim 2.

9. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim 1.

10. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim 2. 

1. A 1-HYDROXY-1-(4-AMINOPHENYL POLYMETHINE) NAPHTHALAN COMPOUND HAVING THE FOLLOWING STRUCTURAL FORMULA:
 2. A compound as set forth in claim 1 having the following structural formula:
 3. A method for preparing a naphthalan compound as set forth in claim 1 comprising reacting one molar equivalent of a p-aminobenzaldehyde compound with one molar equivalent of a hydroxy naphthalan compound having the following structural formula:
 4. A method for preparing a naphthalan compound as set forth in claim 1 comprising reacting one molar equivalent of a 3-(p-aminophenyl) propenal compound with one molar equivalent of a hydroxy naphthalan compound having the following structural formula:
 5. A method for preparing a naphthalan compound as set forth in claim 1 comprising reacting one molar equivalent of a 5-(p-aminophenyl) pentadienal compound with one molar equivalent of a hydroxy naphthalan compound having the following structural formula:
 6. A method as set forth in claim 3 wherein said p-aminobenzaldehyde compound is p-dimethylaminobenzaldehyde.
 7. IN A PRESSURE-SENSITIVE REDORDING SYSTEM COMPRISING A LAYER OF MICROCAPSULES CONTAINING A SUBSTANTIALLY COLORLESS COLOR PRECURSOR COMPOUND ANDAL LAYER OF AN ELECTRON-ACCEPTOR MATERIAL, THE IMPROVEMENT WHICH COMPRISES UTILIZING, AS SAID COLOR PRECURSOR COMPOUND, A NAPHTHALAN COMPOUND AS SET FORTH IN CLAIM
 1. 8. In a pressure-sensitive recording system comprising a layer of microcapsules containing a substantially colorless color precursor compound and a layer of an electon-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim
 2. 9. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement Which comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim
 1. 10. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a naphthalan compound as set forth in claim
 2. 